Maybe "Can't" is too strong but some areas are very hard to self-teach. One reason is stumbling blocks. In academia you have TAs and fellow students who can spe

Maybe "Can't" is too strong but some areas are very hard to self-teach. One reason is stumbling blocks. In academia you have TAs and fellow students who can spend half an hour explaining you a hard concept. Asking on stackexchange cannot always beat that. The other reason is motivation. In academia you are being prodded towards the next milestone. On your own you need to set own milestones and find internal motivation to reach each one.